1. Field of the Invention
The invention relates generally to the field of ‘smart’ safety gear. More particularly, the invention relates to calibration method for environmental sensors attached to a ‘smart’ wearable device.
2. Description of the Related Art
Environmental sensors require periodical performance calibration in order to reconfirm or reestablish their measurement accuracy. Calibration is necessary because most sensors tend to have some zero drift over time in either the positive or negative direction. This zero drift of the sensor readings over time may be compensated for or adjusted by periodic zero calibrations utilizing a known calibration quantity of an element. A similar problem exists with respect to the sensor span signal. Environmental sensors also have a tendency to slowly lose sensitivity with time, so that the span, or range of response from the zero baseline response for a given concentration, decreases over the useful life of the sensor. This loss of sensitivity may similarly be corrected for or adjusted by periodic span calibrations of the sensor circuitry utilizing a predetermined quantity of an element, in order to establish a desired proportionality between the measured signal and the quantity of an element monitored by the sensor device.
Today there are many methods and devices for calibration of static and portable sensors. However, conventional calibration systems are not designed to accommodate calibration of sensors attached to ‘smart’ wearable devices. An object of the present invention to provide improved methods for calibration using stationary or portable calibration device adapted to receive the sensor while it is secured to a ‘smart’ wearable device such as ‘smart’ hardhat, as well as utilize connected property of the said ‘smart’ devices to make calibration process easier and improve measurement accuracy.